The present invention relates to endoscopes, microscopes and boroscopes, in general and to stereoscopic image pick up devices with color imaging capability, in particular.
Stereoscopic image detection devices are known in the art Such devices are required to obtain and provide a combination of small cross section and high image quality. It will be appreciated by those skilled in the art that high image quality, in general, is characterized by stereoscopic vision accuracy, color capabilities, high resolution and illumination requirements.
It is noted that conventional methods, which provide stereoscopic images, require a wider optical path than a monocular one. Such a widened optical path enlarges the cross-section required for the detection device considerably. Hence, the requirement for a small cross section is not maintained.
U.S. Pat. No. 5,527,263 to Zobel et al., is directed to a dual optical path stereo endoscope with simple optical adjustment. U.S. Pat. No. 5,776,049 to Takahashi, is directed to a xe2x80x9cStereo Endoscope Imaging Apparatusxe2x80x9d and provides a device which utilizes a combination of two optical paths with two CCD units, capable of variable zoom.
Auto-stereoscopic devices, which utilize one optical system to provide a stereo effect, are also known in the art. Such a device is provided in U.S. Pat. No 5,603,687 to Hori et al., which is directed to a device with two parallel optical axis and two CCD elements. Hori selected an asymmetrical approach, wherein one optical channel has a large aperture for light and details and the other optical channel provides a parallax image for stereoscopic imagery to the proximal CCD.
U.S. Pat. No 5,613,936 to Czarnek et al., is directed to a stereoscopic endoscope device which utilizes light polarization and time multiplexing in order to transmit each different polarized image corresponding to left and right images multiplexed in time, through one optical channel that transfers images from the lateral side of the endoscope shaft. This endoscope has to be inserted deeper into the human cavity to receive a stereo image. It must also be used with a head mounted display device called xe2x80x9cswitched shutter glassesxe2x80x9d that causes eye irritation. It is noted that according to Czarnek each image is received in 25% of original quality. As much as 50% of the light received fro the object, is lost due to polarization considerations and as much as 50% of the remaining information is lost due to channel switching.
U.S. Pat. No. 5,588,948, to Takahashi et al., is directed to a Stereoscopic Endoscope. The stereo effect is produced by having a dividing pupil shutter, which splits the optical path onto the left and right sides, and the up and down sides. These sides are alternatively projected on a proximal image pickup device, using time multiplexing. According to another aspect of this reference includes a distal CCD, which is divided to left and right sides with a shading member separating them, for achieving space multiplexing.
U.S. Pat. No. 5,743,847 to Nakamura et al, is directed to a xe2x80x9cStereoscopic Endoscope Having Image Transmitting Optical-System And Pupil Dividing Unit That Are Axially Movable With Respect To Each Otherxe2x80x9d, which uses a plural pupil dividing means and one optical channel. U.S. Pat. No. 5,751,341 to Chaleki et al, is directed to a xe2x80x9cstereoscopic endoscope systemxe2x80x9d, which is basically a two channel endoscope, with one or two proximal image sensors. A rigid sheath with an angled distal tip could be attached to its edge and be rotated, for full view.
U.S. Pat. No. 5,800,341 to Mckenna et al, who is directed to an xe2x80x9cElectronically Steerable Endoscopexe2x80x9d, which provides different fields of view, without having to move the endoscope, using a plurality of CCD cells and processing means. U.S. Pat. No. 5,825,534 to Strahle, is directed to a xe2x80x9cStereo Endoscope having a Folded Sight Linexe2x80x9d including stereo-endoscope optical channel, having a sight line folded relative to tube axis.
U.S. Pat. No. 5,828,487 to Greening et al, is directed to a xe2x80x9cstereoscopic viewing system using a two dimensional lens systemxe2x80x9d which in general, provides and alternative R-L switching system. This system uses a laterally moving opaque leaf, between the endoscope and the camera, thus using one imaging system. U.S. Pat. No. 5,594,497 to Ahem, describes a distal color CCD, for monocular view in an elongated tube.
The above descriptions provide examples of auto-stereoscopic inventions, using differ switching techniques (Time division multiplexing) and polarization of channels or pupil divisions (spatial multiplexing), all in an elongated shaft. When color image pick up devices are used within these descriptions, the system suffers from reduced resolution, loss of time related information or a widened cross section.
The issue of color imagery or the issue of a shaft-less endoscope is not embedded into any solution.
To offer higher flexibility and to reduce mechanical and optical constraints it is desired to advance the image pick-up device to the frontal part of the endoscope. This allows much higher articulation and lends itself easily to a flexible endoscope. Having a frontal pick up device is in compromise with having a high resolution color device due to size constraints (at this time).
U.S. Pat. No. 5,076,687 to Edelson, is directed to an xe2x80x9cOptical Ranging Apparatusxe2x80x9d which is, in general a depth measuring device utilizing a lenticular lens and a cluster of pixels.
U.S. Pat. No. 5,760,827 to Faris, is directed to xe2x80x9cPixel data processing system and for producing spectrally multiplexed images of three-dimensional imagery for use in viewing thereofxe2x80x9d and demonstrates the use of multiplexing in color and as such offers a solution for having a color stereo imagery with one sensor. Nevertheless, such a system requires several sequential passes to be acquired from the object, for creating a stereo color image.
It is an object of the present invention to provide a novel system for stereoscopic imaging using a lenticular lens layer and a sensor array, and a novel method for operating the same, which overcome the disadvantages of the prior art.
In accordance with the present invention, there is thus provided a stereoscopic device, which includes a lenticular lens layer and a color light sensor array. The lenticular layer includes a plurality of lenticular elements. Each of the lenticular elements is located in front of a selected group of the light sensors of the sensor array, thereby directing light from different directions to different light sensors within the selected group of the light sensors.
In accordance with a further aspect of the invention, there is provided a stereoscopic device, which includes a lenticular lens layer and a light sensor array, including a plurality of light sensors, where each of the light sensors detects light at a predetermined range of wavelengths.
The stereoscopic device according to the invention can be constructed as a large-scale device, such as a television camera or a small-scale device such as an endoscope.
In a stereoscopic device according to the invention, each of the lenticular elements includes light directing means, which distinguish between at least two directions of light. For example, each of the lenticular elements can be shaped in a general semi-cylindrical shape. Each of the lenticular elements can alternatively include light directing means, which distinguish between four directions of light. For example, such a lenticular element can be shaped in a general semispherical shape.
According to one aspect of the invention, each of the selected groups of the light sensors includes an even number of light sensors. According to another aspect of the invention, each of the selected groups of the light sensors includes an odd number of light sensors.
The stereoscopic device of the invention can further include an illuminating unit. This light illuminating unit can surround the lenticular lens layer. An illumination unit according to the invention includes a light source, a light distribution unit and light guiding means connected between the light source and the light dispersing unit. The light guiding means guides light from the light source to the light dispersing unit. According to one aspect of the invention, the light dispersing unit surrounds the lenticular lens layer.
The light illuminating unit can produce light in a predetermined range of wavelengths. According to another aspect of the invention, the light illuminating unit produces at least two alternating beams of light, where each of the beams of light is characterized as being in a different range of wavelengths.
The stereoscopic device according to the invention, can further include a controller connected to the array of light sensors. This controller produces an image for each of the different directions, by combining data received from the light sensors respective of each of the different directions.
This controller can be connected to the array of light sensors. Accordingly, the controller produces an image for each combination of a selected one of the different directions and a selected one of the beams of light, by combining data received from the light sensors respective of each of the different directions, with respect to the currently illuminating one of the beams of light.
The stereoscopic device according to the invention can further include capturing means, connected to the array of light sensors, for capturing data received from light sensors and a storage unit for storing the captured data. The stereoscopic device can further include a stereoscopic display unit, connected to the controller, for producing the image in a stereoscopic manner. The produced image can be partially stereoscopic.
The predetermined ranges of wavelengths, which are applicable for the light sensors as well as for the illumination light beams can be selected from the list consisting of substantially visible red color light, substantially visible green color light, substantially visible blue color light, substantially visible cyan color light, substantially visible yellow color light, substantially visible magenta color light, substantially infra-red light, substantially ultra-violet light, visible light, and the like.
For example, either the light sensor array or the light beams can include a color combination of red-green-blue (RGB), cyan yellow magenta green (CYMG), a white light color combination and the like.
In accordance with a further aspect of the invention, there is thus provided a method for detecting a stereoscopic image. The method includes the steps of splitting light which arrives from different directions, using a lenticular lens layer, thereby producing at least two images, which are intertwined in a master image, and detecting the master image.
The method can further include the step of reconstructing each of the images from the master image. In addition the method can further include the step of displaying the images using a stereoscopic display device.
Furthermore, the method can include the step of simultaneously displaying the images on a stereoscopic display device.
In addition, the can further include the steps of sequentially illuminating a detected area with alternating beams of light, of different ranges of wavelength, and associating the master image in time, with the currently illuminating ranges of wavelength.
The step of reconstructing can include the steps of determining a range of wavelengths for each pixel within each one of the images, and determining an intensity level for each pixel within each one of the images.
The step of reconstructing can further include the steps of selecting one of the pixels, associated with a predetermined range of wavelengths, determining the pixels associated with another range of wavelengths, in the vicinity of the selected pixel, calculating an approximated level of the other range of wavelengths at the location of the selected pixel, and starting again from the step of selecting.